JPH0479070A - Sound signal recorder - Google Patents

Abstract

PURPOSE:To enable the recording of four channel sound signals by a two channel recording means by multiplexing sound signals of left, center and rear channels out of the four channel sound signals of 3-1 system, multiplexing the right, center and rear channel sound signals, and forming their respective sound signals accordingly. CONSTITUTION:The recorder is provided with a matrix circuit 2 for forming the 1st channel sound signal by multiplexing the left channel, center channel and rear channel sound signals out of the four channel sound signals of the 3-1 system consisting of the left channel, the right channel, the center channel and the rear channel and also for forming the 2nd channel sound signal by multiplexing the right channel, center channel and rear channel sound signals and a recording means 3 for recording these 1st channel and 2nd channel sound signals. By this method, the four channel sound signals of the 3-1 system are recorded by the two channel recording means without deteriorating sound quality greatly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a 3-1 system four-channel stereo audio signal recording device.

[Summary of the Invention 1] The present invention relates to a recording device for a 3-1 type four-channel stereo audio signal, and includes a 3-1 type four-channel stereo audio signal recording device consisting of a left channel, a right channel, a center channel, and a rear channel.
Among the audio signals of the channels, the audio signals of the left channel, the center channel, and the rear channel are weighted and mixed to form the audio signal of the first channel, and the audio signals of the right channel, the center channel, and the rear channel are weighted. It has a matrix circuit that mixes the audio signals of the second channel and recording means that records the audio signals of the first channel and the second channel. -1
This system allows audio signals for four channels to be recorded without significantly deteriorating the sound quality.

[Prior art] The high-definition system has a screen aspect ratio close to that of a movie, allowing you to enjoy images with realistic windows. Provided. For example, in the MtJSE system for broadcasting the high-definition video signal on one channel of satellite broadcasting, the sampling frequency is 32
There are two modes: A mode, which can send 4-channel audio signals at a sampling frequency of 48 kHz, and B mode, which can send 2-channel audio signals at a sampling frequency of 48 kHz.
In the mote, it is possible to enjoy 3-1 stereo sound using the four-channel audio signals.

As shown in Figure 4, the 3-1 stereo sound system consists of a right speaker R3 in front of the right of the viewer, a center speaker C3 directly in front of the viewer, a left speaker LS in front of the left, and a surround speaker SS in the rear. The demodulated audio signals corresponding to the four speakers are supplied to each of the four speakers. One surround speaker SS at the rear may be divided into two rear left and right speakers, and in this case, the same audio signal is supplied to the two rear left and right speakers. (7) In order to record a 3-1 system four-channel stereo audio signal together with a video signal on a video tape recorder (VTR), a recorder capable of recording four or more channels of audio signals is conventionally used; Audio signals of the right channel R1, the center channel C1, the left channel L, and the rear channel S were recorded respectively.

[Problem to be Solved by the Invention 1] However, there are cases where it is desired to record an audio signal having the same effect as the four-channel audio signal of the 3-1 system using two channels if possible. For example, audio signals such as ground music, narration, etc. may be recorded on a videotape on which the four-channel audio signals have been recorded by so-called dubbing.

At this time, if you want to completely preserve the already recorded 3-1 stereo audio as it is, you will need to increase the number of channels on the recorder by the number of channels you want to dubbing, but only for such dubbing. Increasing the number of channels increases the amount of videotape consumed, so it is not a good idea as a format.

In addition, among the audio signals of the 3-1 method, the audio signals of the center channel C and rear channel S are relatively less important, so there is a method of recording 2-channel stereo audio signals in these 2-channel portions by dubbing. can also be considered. However, after the audio signals of the center channel C and the rear channel S are canceled in this way, the remaining two
Even if only the audio of the channel was played back, the sound quality deteriorated significantly, and the sound was far from providing the original sense of realism.

At this time, if the 3-1 stereo sound can be recorded on two channels, desired audio signals can be dubbed on the remaining two channels.

In view of the above, an object of the present invention is to make it possible to record four-channel audio signals of the 3-1 system in two channels without significantly degrading the original sound quality.

[Means for Solving the Problems] The audio signal recording device according to the present invention records audio signals of four channels in a 3-1 format consisting of a left channel, a right channel, a center channel, and a rear channel, as shown in FIG. 1, for example. The audio signals of the left channel, center channel and rear channel are weightedly mixed to form a first channel audio signal, and the audio signals of the right channel, center channel and rear channel are weighted and mixed to form a second channel audio signal. a matrix circuit (2) for forming audio signals of the first channel and the second channel;
and recording means (3) for recording the audio signals of the channels.

[Function] According to the present invention, the audio signal of the first channel includes the audio signals of the center channel and the rear channel in addition to the audio signal of the left channel, and the audio signal of the second channel
The audio signal includes audio signals from the center channel and rear channels in addition to the audio signal from the right channel.

Therefore, when the audio signals of the first channel and the second channel are reproduced from the recording means, audio close to the four-channel stereo audio of the 3-1 system can be obtained.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. In this example, the decoder and VT of MUSE
The present invention is applied to a recording/reproducing device made of R. Although this recording and reproducing apparatus can record and reproduce video signals as well as audio signals, circuits related to video signals are omitted.

FIG. 1 shows the recording system of this example, and in this FIG.
1) is a tuner that functions as a MUSE system decoder, and when the program being received by this tuner (1) uses 3-1 system stereo audio, this tuner (1) decodes the 3-1 system. 4-channel audio signals of the system are output. Of these four channels of audio signals,
left channel.

The center channel, rear (F') channel and right channel audio signals are designated L, C, S and R, respectively.

(2) is the recording system matrix as a whole, and (3) is the video signal as well as the first channel (lch) to the fourth channel (
4ch) is capable of independently recording audio signals of 4 channels on tape, and supplies the audio signals of these 4 channels output from a tuner (1) to its recording system matrix (2), and this recording system 71 - The 4-channel audio signal output from the IJ box (2) is recorded on its recorder (3).
). In this recording matrix (2),
The audio signal C of the left channel is applied to one input of the adder (4), and the audio signal C of the center channel is applied with a coefficient of 0.
The audio signal S of the rear channel is applied to one input of the adder (6) via a multiplier (5) that multiplies by 7.
．． It is fed to the other input of the adder (6) via a multiplier (7) which multiplies it by 7.

Also, the audio signal R of the rear channel is supplied to one input part of the adder (8), and the output of the adder (6) is supplied to the adder (4).
) and the other input of the adder (8). In this case, assuming that the signal output from the adder (4) is L' and the signal output from the adder (8) is R', these signals L' and R' are respectively expressed by the following equations.

L'=L+0.7C+0.7S...
・(1)R'-R+0.7C+0.7S ・・
...(2) Then, the signal L' expressed by equation (1) and the signal R' expressed by equation (2) are sent to the recorder (3) for the first channel (lch) and the second channel (2ch), respectively. ), and the audio signals C and S are supplied as they are to the recorder (3) as audio signals of the third and fourth channels, respectively. The recording @(3) shows the audio signals L' of those four channels.

R', C and R are independently recorded on the tape in a format corresponding to the video signal. However, for example, the third channel and the fourth channel
0.7C and 0.7S respectively as the audio signal of the channel
Another possible method is to record.

Figure 2 shows the reproduction system of this example, and in this Figure 2, (
9) is a playback device corresponding to the recorder (3) in the example in Figure 1, and when the audio of the program recorded on the tape of this playback device (9) is 3-1 stereo sound, this The reproducing device (9) outputs the four-channel audio signals L', R', C, and S recorded in the example shown in FIG.

(10) shows the reproduction system matrix as a whole, and (11) shows the amplifier that independently drives the four-channel speakers consisting of the left channel, center channel, rear channel, and right channel, and these are output from the playback device (9). The 4-channel audio signal is converted into a reproduction matrix (10
), and the four-channel audio signal output from this reproduction matrix (10) is supplied to its amplifier (11). In this reproduction matrix (10), the first
The audio signal L' of the channel is fed to one input of the adder (12), and the audio signal C of the third channel is inputted by the coefficient -0.
, 7 to one input of the adder (14), and the audio signal S of the fourth channel is supplied to one input of the adder (14) via a multiplier (15) that multiplies the coefficient -0,7. and the other input of the adder (14).

Also, the second channel audio signal R' is sent to an adder (16).
and the output of the adder (14) is commonly supplied to the other input of the adder (12) and the other input of the adder (16). In this case, because of the relationship between equations (1) and (2) above, if the signal output from the adder (12) is Ll and the signal output from the adder (16) is R1, these signals L1 and R1 are each represented by the following formula.

L 1 = L'-0,7C-0,7S = L
...(3) R1=R'-0,7C-0,7
S = R (4) That is, the signal L1 output from the adder (12) is equal to the audio signal of the left channel of the tuner (1) in FIG. The signal R1 is equal to the right channel audio signal R output from the tuner (1).

Then, the signal R is supplied to the amplifier (11) as left channel and right channel audio signals, respectively.
The audio signal C of the third channel and the audio signal S of the fourth channel are supplied as they are to the amplifier (11) as audio signals of the center channel and rear channel, respectively. The four speakers output audio signals of these four channels through the amplifier (11), and audio corresponding to R, C, and R.

To explain the operation of this example, if you simply want to record and reproduce 3-1 stereo sound, it is sufficient to record in the example shown in FIG. 1 and reproduce it in the example shown in FIG.

Since the reproduction matrix (10) of the second example performs the inverse calculation of the recording matrix (2) of the example of FIG. 1, the reproduced audio is the same 3-1 system four-channel stereo audio as the conventional one.

Next, after recording 4-channel audio signals in the 3-1 system using the recording system shown in the example in Figure 1, 2-channel stereo audio (
When recording background music (BC, M), narrations, memos, comments, etc.) during dubbing, for example, a switching circuit (not shown) is used to match the video being played back to the recording device (3). Perform dubbing on channels 3 and 4. Then, in order to play back the audio after the dubbing, the audio signal L' of the first channel and the audio signal of the second channel of the playback device (9) can be reproduced without using the reproduction system matrix (10) shown in FIG. The signal R' is individually supplied to the amplifier (11) as left channel and right channel audio signals.

If the dubbing audio is just a memo, it may not be necessary to play it at the same time, but if it is BGM, etc., it may be added to the left channel and right channel audio and supplied to the amplifier (11). . Therefore, in any case, from the left channel speaker and right channel speaker connected to the speaker (11), respectively, the equation (
Audio signals L' and R' represented by 1) and (2)
The audio including the audio corresponding to is output.

Regarding this, when listening to normal two-channel stereo audio, the right channel speaker R-3 is placed in front of the right of the viewer, and the left channel speaker LS is placed in front of the left, as shown in Figure 3. .

Then, 2
Channel stereo audio and original 2 as shown in Figure 3
When comparing audio produced as channel stereo audio, it has been found that the quality of the former is within an acceptable range compared to the quality of the latter. Furthermore, when listening to 3-1 system 4-channel stereo audio in 2-channel stereo arranged as shown in Figure 3, these equations (1) and (2) are generally used.
It is recommended to use the audio signals L' and R' obtained by the conversion of .

Therefore, according to this example, even if two audio channels of the recorder (3) are used for dubbing, the remaining two channels are filled with audio signals L' and R' according to equations (1) and (2). Since the audio signals of these two channels are recorded, there is an advantage that by reproducing the audio signals of these two channels, it is possible to listen to audio with a quality close to that of the original 3-1 system four-channel stereo audio.

In the above embodiment, a 2-channel stereo audio signal is post-recorded, but a 3-1 system 4-channel stereo audio signal may also be post-recorded. In this case,
Audio signals L' and R' are obtained from the four-channel audio signals by equations (1) and (2), and these audio signals L'
and R' are recorded on the third and fourth channels of the recorder (3) in FIG. According to this method, there is an advantage that two sets of 4-channel audio in the 3-1 format can be recorded on the 4-channel audio channels.

Furthermore, in equations (1) and (2) of the above embodiment, 0.7 times the center channel sound C and 0.7 times the rear channel sound S are added to the right channel sound R and the left channel sound R, respectively. However, in general, the audio signals L' and R' may be obtained using the following formulas: R'-αL + βC+γS (5) R'=αR
+βC+TS (6) In these equations (5) and (6), α, β, and T are each coefficients whose absolute values are, for example, 1 or less. Correspondingly, the reproduction system matrix (10) in FIG. 2 needs to be transformed so as to obtain the original audio signal, R, C, and S by inverse transformation of equations (5) and (6).

It goes without saying that the present invention is not limited to the above-mentioned embodiments, and that various configurations can be adopted without departing from the gist of the present invention.

[Effect 1 of the Invention According to the present invention, the recording means for two channels can achieve the 3-
There is an advantage that audio signals for four channels of one system can be recorded without significant deterioration in sound quality.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a recording system according to an embodiment of the present invention, and FIG.
3 is a diagram showing the arrangement of a two-channel stereo, and FIG. 4 is a diagram showing the arrangement of a 4-channel stereo of the 3-1 system. (1) is a tuner, (2) is a recording matrix, (3)
is a recorder, and (5) and (7) are multipliers, respectively.

Claims (1)

[Claims] Of the four-channel audio signals of the 3-1 system consisting of the left channel, right channel, center channel, and rear channel, the audio signals of the left channel, center channel, and rear channel are weighted and mixed. a matrix circuit for forming an audio signal of a first channel and weight-mixing the audio signals of the right channel, center channel, and rear channel to form an audio signal of a second channel; and a recording means for recording an audio signal of a channel.